* {
    /* 去掉默认样式 */
    margin: 0;
    padding: 0;
    /* 去掉默认无序列表相关样式 */
    text-decoration: none;
    list-style-type: none;
}

body {
    background-color: #edeff3;
}

.center {
    margin: 0 auto;
}

.head {
    width: 1200px;
    height: 42px;
    margin: 30px auto;
}

.head-logo {
    float: left;
    width: 195px;
    height: 42px;
    background-image: url("../imgs/xuecheng-logo.png");
    background-size: 195px, 42px;
    margin-right: 70px;
}

.nav li {
    float: left;
    line-height: 42px;
    margin-right: 45px;
    font-size: 20px;
    font-weight: normal;
}

.nav li:hover {
    border-bottom: solid 3px #00A3FA;
}

.nav li>a {
    color: #020305;
}

.search {
    float: left;
    width: 412px;
    height: 42px;
    margin-left: 50px;
}

.search-input {
    float: left;
    width: 360px;
    height: 38px;
    border: solid 2px #04A3FF;
    border-right: none;
    color: #BDBEC0;
    /* 文字缩进 */
    text-indent: 20px;
    font-weight: normal;
    font-size: 15px;
}

.search-button {
    float: left;
    width: 50px;
    height: 42px;
    border: none;
    background-image: url(../imgs/btn.png);
    background-size: 50px, 42px;
}

.user {
    float: right;
    width: 178px;
    height: 42px;
}

.user-img {
    float: left;
    width: 40px;
    height: 40px;
    border-radius: 5px;
    border: solid 1px black;
    margin-left: 30px;
    background-repeat: no-repeat;
    background-image: url(../imgs/head-photo.jpg);
    background-size: 46px, 46px;
    justify-content: center;
    align-items: center;
}

.user-name {
    float: left;
    line-height: 42px;
    margin-left: 10px;
    color: #656668;
}